[wasm] Optimize interp->native transitions. (#20034)

* [wasm] Optimize interp->native transitions.

* Generate tables of signatures/transition functions.
* Add mono_wasm_get_interp_to_native_trampoline () function to look up the transition function
for a signature.
* Cache the transition function in a imethod->method_data slot.

Previously, we were calling a mono_wasm_interp_to_native_trampoline () function and a generated
icall_trampoline_dispatch () function which added a lot of overhead.

* Avoid sharing cache entries.

1 files changed, 9 insertions, 50 deletions

diff --git a/mcs/tools/wasm-tuner/InterpToNativeGenerator.cs b/mcs/tools/wasm-tuner/InterpToNativeGenerator.cs
index 8c5adb6ff9c..e110dd9b27c 100644
--- a/mcs/tools/wasm-tuner/InterpToNativeGenerator.cs
+++ b/mcs/tools/wasm-tuner/InterpToNativeGenerator.cs
@@ -295,60 +295,19 @@ class InterpToNativeGenerator {
 			w.WriteLine ("\n}\n");
 		}
 
-		w.WriteLine ("static void\nicall_trampoline_dispatch (const char *cookie, void *target_func, InterpMethodArguments *margs)");
-		w.WriteLine ("{");
-
-		/*
-		if (args.Any(a => a == "--flat")) {
-			for (int i = 0; i < cookies.Length; ++i) {
-				var c = cookies [i];
-				w.Write ("\t");
-				if (i > 0)
-					w.Write ("else ");
-				w.WriteLine ($"if (!strcmp (\"{c}\", cookie))");
-				w.WriteLine ($"\t\twasm_invoke_{c.ToLower ()} (target_func, margs);");
-			}
-			w.WriteLine ("\telse {");
-			w.WriteLine ("\t\tg_error (\"CANNOT HANDLE COOKIE %s\\n\", cookie);");
-			w.WriteLine ("\t}");
-		} else {
-		*/
 		Array.Sort (signatures);
-		WritePartition (w, signatures, 0);
-		w.WriteLine ("\tg_error (\"CANNOT HANDLE COOKIE %s\\n\", cookie);");
-
-		w.WriteLine ("}");
-	}
-	
-	static void WritePartition (StreamWriter w, IEnumerable<string> set, int pos = 0, int depth = 0) {
-		var prefix = "\t";
-		for (var c = 0; c < pos; c++)
-			prefix += "\t";
 
-		var checks = 0;
-		
-		var groups = set.OrderBy (s => -s.Length).Where (s => s.Length > pos).GroupBy (s => s.Skip(pos).First().ToString());
-		foreach (var g in groups) {
-			w.WriteLine ($"{prefix}{Elif (checks)} (cookie[{pos}] == '{g.Key}') {{");
-			WritePartition (w, g.ToList (), pos + 1, checks + depth);
-			w.WriteLine ($"{prefix}}}");
-			checks++;
-		}
-
-		var hits = set.Where (s => s.Length == pos);
-		if (hits.Any ()) {
-			w.WriteLine ($"{prefix}{Elif (checks++)} (cookie[{pos}] == '\\0') {{");
-
-			var h = hits.First ();
-			w.WriteLine ($"{prefix}\t// found: {h} depth {pos + checks + depth}");
-			w.WriteLine ($"{prefix}\twasm_invoke_{h.ToLower ()} (target_func, margs);");
-			w.WriteLine ($"{prefix}\treturn;");
-			w.WriteLine ($"{prefix}}}");
-		}
+		w.WriteLine ("static const char* interp_to_native_signatures [] = {");
+		foreach (var sig in signatures)
+			w.WriteLine ($"\"{sig}\",");
+		w.WriteLine ("};");
 
-		string Elif (int c) {
-			return c == 0 ? "if" : "else if";
+		w.WriteLine ("static void* interp_to_native_invokes [] = {");
+		foreach (var sig in signatures) {
+			var lsig = sig.ToLower ();
+			w.WriteLine ($"wasm_invoke_{lsig},");
 		}
+		w.WriteLine ("};");
 	}
 
 	class EmitCtx